Hot melt adhesives are useful for bonding articles such as cardboard boxes, bottle labels, and the like. Hot melt adhesive compositions are thermoplastic materials that can be heated to a molten state and applied to one or more substrates for bonding. Conventional hot melt adhesives form a bond as the molten adhesive cools and solidifies while in contact with the substrates to be bonded. Pressure-sensitive hot melt adhesives are applied at elevated temperature, yet remain tacky after cooling and can be bonded to a substrate at room temperature using light pressure.
Hot melt adhesives typically comprise a polymer resin, a tackifier, and a wax. The polymer resin provides the adhesive formulation with its strength and adhesive characteristics. Tackifying agents are added to give the adhesive tack and to adjust its viscosity. Wax is added to reduce the overall viscosity of the adhesive so that is liquefies upon heating. The wax also helps to control the open time and set speed of the adhesive.
Waxes that are commonly used in hot melt adhesives include petroleum-derived waxes such as synthetic polyethylene waxes, Fischer-Tropsch waxes, microcrystalline wax, and paraffin waxes. Given that the world's supply of petroleum is finite, it is desirable to provide hot melt adhesive compositions comprising waxes that can be made from renewable starting materials. For example, the replacement of paraffin wax, microcrystalline wax, polyethylene wax, and Fisher-Tropsch wax in hot melt adhesives with waxes based on renewable starting materials is desired.